Add Python calculator example demonstrating code featurizer usage

[Copilot]

Issue requested more examples showing how to use the featurizer.

Changes

• example_calculator.py: Python calculator with arithmetic operations (add, subtract, multiply, divide) demonstrating featurization on Python code vs existing C example
• example_usage.py: Standalone script showing complete workflow—load code from CSV, find optimal features, generate vectors, save output
• example_calculator.csv: CSV input with calculator code lines following existing format
• README.md: Documents both examples, usage instructions, and explains featurization purpose (code similarity, ML on source code, pattern recognition)
• .gitignore: Excludes generated outputs and Python artifacts

Usage

python3 example_usage.py

Output:

Step 1: Loading code from CSV file...
Total lines loaded: 28
Unique lines: 28

Step 2: Finding optimal feature set...
Non-unique lines remaining: 27, features found: 1 in 0.00 sec.
...
Total features found: 17

Step 3: Generating feature vectors for all lines...
Step 4: Saving results to ./output_example_calculator.csv...

The example demonstrates the complete featurization pipeline with clear output showing progress through each stage.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add new example</issue_title>
<issue_description>We should have more examples of how to use the featurizer</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Add new example #1

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.